1. Field of the Invention
The present invention relates to a casing structure of electronic equipment used in a numerical control device or control devices for various machines.
2. Description of the Related Art
The electronic equipment used in a numerical control device or control devices for various machines comprises a fan motor for cooling the control boards or electronic components provided inside the casing of the electronic equipment. If such electronic equipment is operated for a long period of time in a manufacturing floor such as a factory, moisture, cutting oil and the like contained in the air inside the factory accumulates in the form of mist on the casing of the fan motor. When placing the fan motor at an upper section of the electronic equipment, the moisture and oil accumulated on the casing of the fan motor drip down in the form of water droplets and oil droplets into the electronic equipment and adhere to the control boards and the like of the electronic equipment, causing failures such as shorting of the electronic components and acceleration of deterioration.
FIG. 9 is a cross-sectional diagram showing a structure of attaching a fan motor to conventional electronic equipment. A casing 2 is attached to the back of a display section 1 of the electronic equipment, and a plurality of control boards 3 in which electronic components are disposed in printed boards and the like are stored in this casing 2. An upper wall of the casing 2 is provided with a vent hole 4, and a fan motor 5 is attached in the upper section of this vent hole 4. By operating the fan motor 5, the air inside the casing 2 is drawn and discharged to the outside, thereby cooling the electronic components disposed in the control board 3.
By operating the fan motor 5, moisture, cutting oil or the like contained in the air adhere in the form of mist to a housing 6 of the fan motor 5, are then condensed into a water droplet or oil droplet 7, and falls. This water droplet or oil droplet 7 is generated on a random position and adheres to the control boards 3 or electronic components, causing shorting and failure of the electronic components.
Therefore, for the purpose of improving such problem, Japanese Patent Application Laid-Open No. 9-172281 proposes a configuration in which the bottom section of a fan motor is inclined in a horizontal direction and attached to the casing of electronic component, and water droplets and oil droplets on the bottom section of the fan motor are guided along the bottom section, which is the inclined surface, to reach an end section of the fan motor so that the water droplets and oil droplets do not drop positions of the control boards and the like inside the electronic equipment.
In the invention described in the patent literature described above, the fan motor is simply inclined and attached to the casing. Therefore, depending on the shape of the fan motor, oil and the like adhered to the housing of the fan motor do not always drop in one direction.
Moreover, although water droplets and oil droplets fall vertically on a predetermined region when the fan motor is stopped, the problem is that when the fan motor is driven the water droplets and oil droplets do not drop vertically due to the flow of the air drawn by the fan motor, but adhere to the control boards or electronic components.